Plated article and its manufacture



Patented Dec. 29, 1925.

UNITED STATES J'OSETH A. SMITH, 0F ATTLEBORO, MASSACHUSETTS.

PLATED ARTICLE AND ITS MANUFACTURE.

No Drawing.

To all whom it may concern: 4

Be it known that I, JOSEPH A. SMITH, a citizen of the United States,residing at Attleboro, in the county of Bristol and State ofMassachusetts, have invented certain new and useful Improvements inPlated Articles and Their Manufacture, of which the following is aspecification.

My invention relates to improvements in plated articles and an improvedmethod of their manufacture.

My invention particularly relates to the process of tight coating orinter-alloying a metal article, usually a steel article, with a layer ofa metal of substantially low melting point. I am aware that it is old toelectro-deposit a thin layer of zinc and on subjecting theelectro-plated article to heat to tight coat the zinc to the metal. I amalso aware that it is old to electro-deposit a layer of a metal of asubstantially low melting point such as cadmium to a metal article andby subjecting the article to heat to inter-alloy the cadmium with thearticle to form a protective coating. The disadvantages of either ofthese processes have been as follows: In the heating treatment a largeamount of the electro-deposited la er of zinc or cadmium is oxidizedofi', thereby necessitating the use of a large amount ofelectrodeposited metal and consequent loss of metal. As aninter-alloying takes place between the outer electro-deposit'ed layerand the metal of the article there is always a certain amount of iron orsteel or other base metal employed drawn to the surface in theinter-alloying and so the article becomes not completely rustproof asoften claimed.

In my process I electro-deposit or otherwise coat on the metal articlean intermediate layer of a metal of a substantially low Applicationfiled January 28, 1925.

Serial 1T0. 4,271.

electro-plated articles are heated to the required degree theelectro-deposited metal, crystalline when laid, forms a sheet or tightcoating of metal over the metal article. As in my process I preferablyonly heat the article to an amount below the melting point of theintermediate layer, the outer protective. layer usually remainscrystalline as electro-deposited. The preferably thinner outer layerhowever, prevents the intermediate layer from being oxidized off as itbecomes inter alloyed with the metal of the article, thus effecting agreat saving in metal. As no substantial amount of interalloying takesplace between the outer layer and the intermediate layer or the metal ofthe article, it is obvious that none of the base metal will be drawn tothe outer surface and that the article is more rust-proof than anyhitherto constructed.

These and such other objects of my invention as may hereinafter appearwill be bestunderstood from a description of the specific method aboutto be described illustrating an embodiment of my invention.

he article to be plated which may comprise a musical instrument wire, aspring or any other suitable metal article herein called the base metalarticle is cleaned and polished in the usual manner to prepare for theelectro-deposition of the plating process by cleaning it of all rust anddirt preferably with a very fine grad of emery cloth. If necessary itmay also be cleaned by dipping it in a dilute sulfuric acid or otherchemical solution and finally in water.

The next step in the process consists in coating on the base metal anintermediate layer of a metal of a substantially low melting point whichis preferably accomplished by an electro-plating bath of the followingcomposition: Chloride of zinc 4 ozs., cyanide of potassium 4 ozs.,sal-ammoniac 2 ozs. to each gallon of water. A suflicient deposit ofthis solution may be obtained in five minutes with a volta e of six,though a heavier deposit may be laid thereon if desired by plating for alonger period.

The article is then preferably rinsed in water and then coated with alayer of a metal of a substantially higher melting als may be employed.

point preferably by electro-plating a layer of nickel thereon. Asuitable electro-platin bath for this purpose is double nickel sa ts 802s., single nickel salts 2 02s., boracic acid 1 oz. to each gallon ofwater. A sufficient coating may be obtained in about five minutes with avoltage of 2 The article is then preferably dipped into a yellow ochresolution which tends to prevent the formation-of heat spots during theheating treatment, though this step may be dispensed with if thong tadvisab e.

The article is then heated in a furnace or a gas flame preferably at atemperature of substantially 600 F. for an appreciable length of timevarying from five minutes to four hours to cause an inter-alloying ofthe intermediate layer with the base metal of the article and to changethe intermediate layer from a crystalline structure into a sheet. Theouter preferably thinner nickel layer is not appreciably afiected by theheat treatment at this temperature and may remain as a protective layer.Even though the protective crystalline nickel layer may become worn inuse there will remain a tight coated intermediate zinc layer underneathvery resistant to wear. The furnace may be heated up to 600 F, thearticle inserted and taken out when the temperature again rises to 600F. to give an inter-alloying suitable for most purposes. After removalfrom the furnace, the ochre solution is washed off and the articlebufi'ed and polished.

As stated in place of zinc other metals of a substantially low meltingpoint such as cadmium, silver, tin or other suitable metals or alloysmay be employed. In place of nickel as the outer protective layer, gold,

silver, copper or other suitable alloys or met- It is obvious that bythis rocess I have provided a metal article having all the advantages ofan article having a coating alloyed thereto and the advanta es of havingan outer coating of metal of a higher melting point.

It is understood that my invention is not limited to the specificprocesses or articles described and that various deviations may be madetherefrom without departing from the spirit and scope of the ap endedclaims.

What I claim as new and esire to secure as Letters Patent is:

l. The process of coating metal articles, which comprises coating-thearticle with an intermediate la er of a metal of a substantially lowmelting point, in coating the intermediate layer with a layer of a metalof a substantially higher melting point and then subjecting the coatedarticle to heat under conditions causing an alloying of the intermediatelayer and the metal of the article without any substantialinter-alloying with the outer layer.

depositing on the intermediate layer a layer of a metal of asubstantially higher melting point and then subjecting the coatedarticle to heat under conditions causing an alloying of the intermediatelayer and the metal of the article without any substantial interalloyingwith the outer layer.

3. The process of coating metal articles which comprises coating thearticle with an intermediate layer of zinc, in coating the zinc layerwith a layer of nickel and then all subjecting the coated article toheat under conditions causing an alloying of the zinc and the metal ofthe article without any substantial inter-alloying with the nickellayer.

- 4. The process of coating metal articles which compriseselectro-depositing on the article an intermediate layer of zinc,electrodepositing on the zinc layer a layer of nickel and thensubjecting the coated article to heat under conditions causing analloyin of the zinc layer and the metal of the artic e without anysubstantial inter-alloying with the nickel layer.

5. The process of coating metal articles,

which comprises coating the article with an intermediate layer of ametal of a substantially low melting oint, in coating the intermediatelayer witli a layer of a metal of a substantially higher melting pointand then subjecting the coated article to a heat somewhat less than themelting point of the metal of the intermediate coated layer for asubstantial period of time to cause an alloying of the intermediatelayer and the metal of the article.

6. The process of coating metal articles which compriseselectro-depositing on the articlev an intermediate layer of metal of asubstantially low melting point, in electrodepositing on theintermediate layer a layer of a metal of a substantially higher meltingpoint and then subjecting the coated article to a heat somewhat lessthan the melting point of the metal of the intermediate coated layer fora substantial period of time to cause an alloying of the intermediatelayer and the metal of the article.

7. The process of coating metal articles which comprises coating thearticle with an intermediate layer of zinc, in coating on the zinc layera layer of nickel and then subjecting the coated article to a heat ofsubstantially 600 F. from five minutes to four hours to cause analloying of the zinc and the metal of the article.

8. The process of coating metal articles whichcomprises'electro-deposting on the armamas a heat of substantially 600F. from five min- 10 ed thereto and an electro-deposited layer 1. v

utes to four hours to cause an alloying of the o a metal of asubstantially higher melting zinc layer and the metal of the article.point thereon.

9. A metal article having a coating of a 11. A metal article having a.coating of 5 metal of a substantially low meltingafaoint zinc alloyedthereto and a coating of mckel alloyed thereto and a coating of a. me ofe thereon. 13 substantially higher melting point thereon. In testimonywhereof I afiix my signature 10. A metal article having a coating of ametal of substantially low melting point 91- JOSEPH A. SMITH.

